awitt333

ok i just bought a 2003 is300 and it has aftermarket headers, air intake, and a full hks exhaust.
when i got it from the dealer the check engine light was and the stability control light flashed every so often. they wouldnt do anything about it cause they suck. they claimed they tried fixing it and it shouldnt have any problems, and here we are. the car is pulling codes that say its running lean. i changed the MAS (mass air sensor) and it ending up working great but then the codes came back. also i changed the plugs as well as oil for regular maintenance.
the problem now is i can just be cruising and i press the gas and it stays around 3k or goes up to about 3500k and stays there even if i press the gas as far as it can go.
anybody with experience with the same problem or anyone that can shed some light on this would be greatly appreciated thanks!

infojunky

Post up the codes. Sounds like the limp mode mine was in when I bought it with a P1349 code.

gunmetal

sounds like oc sensor. did you clean throttle body?